Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

only to observe this civilization, rather than carry on any conversation. There will be an effort to build gigantic radio transmitters that can send messages back to the aliens. But in fact, it may take centuries before any two-way communication is possible with this civilization.
    NEW CLASSIFICATIONS
    The Kardashev classification was introduced in the 1960s, when physicists were concerned about energy production. However, with the spectacular rise of computer power, attention turned to the information revolution, where the number of bits processed by a civilization became as relevant as its energy production.
    One can imagine, for example, an alien civilization on a planet where computers are impossible because their atmosphere conducts electricity. In this case, any electrical device will soon short-circuit, creating sparks, so that only the most primitive forms of electrical appliances are possible.
    Any large-scale dynamo or computer would quickly burn out. We can imagine that such a civilization might eventually master fossil fuels and nuclear energy, but their society would be unable to process large amounts of information. It would be difficult for them to create an Internet or a planetary telecommunications system, so their economy and scientific progress would be stunted. Although they would be able to rise up the Kardashev scale, it would be very slow and painful without computers.
    Therefore, Carl Sagan introduced another scale, based on information processing. He devised a system in which the letters of the alphabet, from A to Z, correspond to information. A Type A civilization is one that processes only a million pieces of information, which corresponds to a civilization that has only a spoken language but not a written one. If we compile all the information that has survived from ancient Greece, which had a flourishing written language and literature, it is about a billion bits of information, making it a Type C civilization. Moving up the scale, we can then estimatethe amount of information that our civilization processes. An educated guess puts us at a Type H civilization. So therefore, the energy and information processing of our civilization yields a Type .7 H civilization.
    In recent years, another concern has arisen: pollution and waste. Energy and information are not enough to rank a civilization. In fact, the more energy a civilization consumes and the more information it spews out, the more pollution and waste it might produce. This is not an academic question, since the waste from a Type I or II civilization might be enough to destroy it.
    A Type II civilization, for example, consumes all the energy that is produced by a star. Let us say that its engines are 50 percent efficient, meaning that half the waste it produces is in the form of heat. This is potentially disastrous, because it means that the temperature of the planet will rise until it melts! Think of billions of coal plants on such a planet, belching huge amounts of heat and gases that heat the planet to the point that life is impossible.
    Freeman Dyson, in fact, once tried to find Type II civilizations in outer space by searching for objects that emit primarily infrared radiation, rather than X-rays or visible light. This is because a Type II civilization, even if it wanted to hide its presence from prying eyes by creating a sphere around itself, would inevitably produce enough waste heat so that it would glow with infrared radiation. Therefore he suggested that astronomers search for star systems that produce mainly infrared light. (None, however, were found.)
    But this raises the concern that any civilization that lets its energy grow out of control may commit suicide. We see, therefore, that energy and information are not enough to ensure the survival of the civilization as it moves up the scale. We need a new scale, one that takes efficiency, waste heat, and pollution into account. A new scale that does is based on another concept, called entropy.
    RANKING CIVILIZATIONS BY ENTROPY
    Ideally, what we want is a civilization that grows in energy and information, but does so wisely, so that its planet does not become unbearably hot or deluged with waste.
    This was graphically illustrated in the Disney movie
Wall-E,
where in the distant future we have so polluted and degraded the earth that we simply left the mess behind and lead self-indulgent lives in luxury cruise ships drifting in outer space.
    Here’s where the laws of